1. Field of the Invention
The present invention relates generally to passive air induction systems, and more particularly to advanced marine vessel tunnel designs incorporating air induction tubes and distribution slots about the perimeter of the tunnel for marine propulsion systems.
2. Description of Related Art
During rotation of a boat propeller, the hull bottom of the vessel is impacted by energy in the form of shock waves due to the phenomenon referred to as tip cavitation. Cavitation occurs when spiraling low-pressure cavitation voids (vortices) are created by each blade of the propeller during rotation. As these voids migrate to a zone of higher pressure the cavity suddenly collapse leading to a violent “implosion.” This “implosion” produces noise and erratic vibration in the vicinity of the propeller that propagates into the hull structure and eventually onto the boat decks and upper structures of a vessel. As propeller loading increases to meet the demands of heavier boats and increased horsepower these cavitation voids increase in size, the implosion becomes more violent, and thus, the impact on vibration becomes more significant.
U.S. Pat. No. 6,406,341, issued to Morejohn on Jun. 18, 2002, discloses a shallow draft boat hull which incorporates a vent tube in an angled tunnel for the purpose of creating a low pressure area, and dissipating air bubbles in the tunnel. Air bubbles are sucked into a recess and travel upwardly through a tube to be exhausted behind the transom.
U.S. Pat. No. 6,213,824, issued to Small on Apr. 10, 2001, U.S. Pat. No. 6,193,573, issued to Small on Feb. 27, 2001, and U.S. Pat. No. 6,045,420, issued to Small et al., on Apr. 4, 2000, teach a system of hull design, which incorporates centrally placed air induction plenums having planar walls running longitudinally along a section of the hull. Air is introduced into adjacent tunnels which house struts and propellers. The designs are based on critical angular and area formulas for attempted linearization of the relationship between static and dynamic water levels, vessel velocity and engine revolutions per minute.
U.S. Pat. No. 5,957,078, issued to Van Tassel on Sep. 28, 1999, discloses a marine propulsion system and hull design, which includes air ducts, air valves or a combination of both, to introduce air in the propeller tunnel, before the propeller itself. This design is specifically for the purpose of controlling the level of water in the tunnel to optimize the performance of surface-piercing propellers.
The prior art, however, fails either alone or in combination with other references, to teach or suggest the instant engineering designs for an advanced arcuate or semi-circular boat tunnel design incorporating air induction tubes and a complementary curved slot distribution wedge with air outlets, nor any similar or related structure, which was designed for creating a layer of air to absorb energy or shock waves caused by cavitation. The prior art does not disclose or illustrate the components of the instant invention, and likewise does not address the particular problems solved with this marine propulsion system.